1. Field of the Invention
The present invention relates generally to a video displaying apparatus and a fast screen scrolling method for an internet set top box, and more particularly, to an apparatus that minimizes the need for equipped with the memory capacity for storing data to be displayed onto a monitor, and to a method for preparing a pointer address table in the memory. The pointer address table includes start addresses pointing to the start each of scanning lines of TV signal, and a pointer to be read out first in the pointer address table is selected sequentially and circularly, which results in minimum data movement within the memory in screen scrolling up or down mode.
2. Brief Description of the Prior Art
As the internet communication has become prevalent and the number of people using the internet has increased, the development of TV sets capable of connecting to the internet, so called an internet TV, has been launched and some products are already commercially available in the market. Besides having the features of a conventional TV the internet TV can function as a set top box-type internet terminal.
These conventional internet set top boxes employ VGA cards, used commonly in PCs, for displaying information received from the internet on a TV screen. The video displaying apparatus for conventional internet set top boxes comprises, as shown in FIG. 1, a video memory 60 for storing pixel data to be outputted and displayed on a TV screen, a graphic controller 10 for controlling input/output of the video memory 60, and a video signal converter 70 for converting the pixel data outputted from the graphic controller 10 to RGB signals.
In the conventional internet set top boxes, video information corresponding to the size of the video memory 60, for example 256 KB (=64K.times.4), is transferred to the graphic controller 10 and then is converted into pixel data and stored in the video memory 60. Under the control of the graphic controller 10, the stored pixel data are sequentially read out and transmitted to the video signal converter 70, wherein the pixel data are converted into RGB signals. The RGB signals are then converted to TV video signals, i.e., a composite video signal, and finally displayed on a TV screen.
As mentioned above, to process signals, the video conventional internet set top boxes employs a VGA card originally developed for PCs. The VGA cards usually require a video memory capacity of more than 256 KBytes adapting for video data. However, the video memory capacity needed for displaying video images on a TV screen is much smaller than that of the VGA card, which is designed for still image of high resolution. This is because a TV screen has lower resolution than a computer monitor. Also since a TV signal represents a seris of pictures, it is not necessary for the memory to be capable of storing video data corresponding to a full screen. Thus, the use of the VGA card unnecessarily increases the production cost.